Water vapor has been detected around Ceres, one of the largest asteroids in our solar system, by the European Space Agency's infrared Herschel space telescope before it was decommissioned last year.

Ceres, now classified as a dwarf planet, has long been thought to have rocky core and an icy outer layer. While there is no certainty as to where this water is coming from, the ESA suggests this could be due to the sublimation of ice -- the melting of ice from solid state directly to vapor form. The quantity of gas being ejected is not large -- 13 pounds every second -- but is undeniably water vapor.

"This is the first time that water has been detected in the asteroid belt, and provides proof that Ceres has an icy surface and an atmosphere," said Michael Küppers of the ESA.

The discovery has been reported in the journal Nature. While the telescope was unable to get a clear image of Ceres, scientists were able confirm the presence of water vapor by observing variations in the water signal around the dwarf planet. They believe that the water is coming from the dark colored regions of the surface of Ceres.

The presence of water vapor in the asteroid belt between Mars and Jupiter will give scientists an understanding of the evolution of the solar system and the distribution of water within it. Scientists will be able to get a better view of Ceres come 2015, when NASA's Dawn mission will provide up-close mapping of its surface.

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